The Chuck Eye Steak - not to be confused with a Chuck Steak or a Chuck Roast.
Our local grocer began carrying these a while back. It's ALMOST a Ribeye steak. The difference is that a Ribeye is cut from the 6th through the 12th rib. The Chuck Eye is cut from the 5th rib only. It is marbled and tender, very much like a Ribeye. Flavor is very similar. The main difference is the price - often less than half the cost of Ribeye!
They're obviously harder to come by, since there is less Chuck Eye per animal. But because they aren't as popular, the cost is low. Traditionally this piece of meat would just be sold as part of the Chuck Roast. I guess someone got wise to the fact that they could slice off the end of a Chuck Roast and sell it as a steak for more money.
In looking for the above link, I discovered that some folks just buy the Chuck Roast and slice it into steaks themselves, as the entire roast is well-marbled and flavorful. With beef prices as they are, I may have to try that as well.
ETA: Posted this because that's what I'm cooking for dinner this evening.